Insight is an experientially derived clear knowing!
It is not an academic or technical knowing. It is a clear knowing from how and what we are thinking and doing.
We think we can rely on the body-mind, our circumstances or our environment. We can’t. The only thing we can rely on is insight, and compassion. One might suggest that insight comes from exercising the mind, which means we can rely on the mind. The truth is that the mind is like a finger, and insight is like the fist. We have to exercise the mind to get to insight but insight is greater than the mind. The mind can go but insight exerts its influence even when our mind forsakes us. Take for instance the insight that things are ceaselessly arising and ceasing.
We might be in the grip of longing and yearning, and our mind might conjure visions of pleasure or pain but if the insight mentioned is embedded in our psyche, we clearly know that whatever is unfolding will pass. So we are better able to manage the push and pull of yearning and expectations. Yearning and expectations are of the mind but our patience and fortitude is of insight. Thus, the sole thing we can always rely on is insight, not the body-mind, not circumstances and not the environment. All of these can change but insight governs the direction we take despite change, and pleasure or pain.